                 image-points1 (map inversion pre-image-points1)
                 image-points2 (map inversion pre-image-points2)
                 image-points3 (map inversion pre-image-points3)]
-            (draw-circle-2 center radius draw-chan)
+            (draw-circle-2 center radius draw-chan
+                           {:stroke :red :fill :grey-2})
             (draw-point image1 draw-chan)
             (draw-point image2 draw-chan)
             (doseq [p image-points1]

  (let [circumcenter (geom/circumcenter [p1 p2 p3])
        _ (println "circumcenter: " circumcenter)]
    (when (contains? options :circumcircle)
      (draw-line p1 circumcenter draw-chan #{})
      (draw-line p2 circumcenter draw-chan #{})
      (draw-line p3 circumcenter draw-chan #{})
      (draw-circle-2 circumcenter (geom/distance p1 circumcenter) draw-chan))
    (draw-line p1 p2 draw-chan #{:perp-bisector})
    (draw-line p2 p3 draw-chan #{:perp-bisector})
    (draw-line p3 p1 draw-chan #{:perp-bisector})
    (when (contains? options :circumcenter)
      (draw-point circumcenter draw-chan))))



(defn draw-line
  "draw line between p1 and p2"
  [p1 p2 draw-chan options color]
  (let [m (geom/midpoint p1 p2)
        l (geom/distance p1 p2)
        [q1 q2 s1 s2] (geom/perp-bisector [p1 p2])]
    (go (>! draw-chan
            [(dt/style {:stroke color :fill :grey-2})
             (dt/point p1)
             (dt/point p2)
             (dt/line [p1 p2])])
